This invention relates to vibrating screens and more particularly to variably sloped vibrating screens.
The aggregate industry utilizes many styles of screen machines to sort aggregates by size. Most screen machines utilize vibration to agitate the mixture of aggregates to promote separation through various sized openings in the screening surfaces. Sorting is achieved by undersized particles passing through the openings in the screening surface and the oversized particles being retained above the screen surface. These machines usually have some type of vibrating mechanism to shake the unit and its screening surfaces. The vibrating mechanisms usually include an unbalanced weight mounted on one or several rotating shafts which when rotated, force a cycling motion into the screen machine.
These screen machines are normally operated in a single orientation which may be either horizontal or inclined.
Fixed inclined screens are constructed so the screen surfaces are sloped, usually toward the discharge end, to aid material movement to the end and off the screen.
Sometimes a screen is designed to be oriented in various sloped positions. This is frequently found in portable equipment that requires a lower profile for travel, as well as multiple sloped positions as needed for various screening applications.
In the past, variable sloped screens have provided for the ability to access an inclined platform by including structure such as multiple ladders for differing angles of inclination of the screen and others have used a stationary ladder, but without a ladder top platform. The Elrus 6×20 uses such a system, but it does not provide access in the transport position and only at a fixed position. The Terex Finlay 694+ Supertrak has a ladder fixed to the end of the walkway platform, but the angle of that ladder changes when the angle of screen is adjusted.
While these systems have provided for variable positions, they did have several drawbacks. One is the safety problem associated with a person moving from a ladder directly to an inclined walkway platform and the difficulty in climbing a ladder when the ladder is laid out and is substantially not vertical.
Consequently, there is a need for improvement in ladder and access platform systems for variable slope vibrating screens.